Unwanted controller reset

[jirkaptr]

The Serial Projector sets the DTR=ON bit in the UART. This usually results in a RESET of the connected controller. For this reason, it is not possible to connect the Serial Projector to an already running controller.
This problem is usually solved by customizing the DTR setting. A suitable place to add the setpoint is the Connections menu.

[knopki]

Thank you for reporting!

Ability to set signals is implemented in #43.
But this problem with DTR=ON and restarting the controller most likely cannot be fixed from this side. According to the Web Serial API specification (and the Chromium implementation), "setSignals()" can only be set on an open port. Thus, it is impossible to set the initial values.

References:

• RTS being set high on port connection WICG/serial#195
• Specify default DTR and RTS output states WICG/serial#177
• https://wicg.github.io/serial/#setsignals-method

[jirkaptr]

Hello @knopki , thank you for your activity. However, I would like to suggest some changes.

A: Menu Connections.

1. What is the meaning of the item “break”? In RS232 etc. “signal ‘break’ on serial port” is not defined.
2. The options default/yes/no in the case of DTR and RTS are chosen inappropriately. The user needs to set one of two values ​​- ON or OFF. The option “default” is not understandable: What value is “default”?
3. Help for DTR, RTS is more of a comment for the programmer, but unusual for practice. The established and short(!) expressions in the industry are “Set ON/OFF”.

B: Unwanted reset
First, a short explanation. Normally, the DTR signal is fed through a derivative RC element to the processor input. The falling edge of DTR causes a RESET of the processor.
To clarify the behavior of DTR/RESET, I used an oscilloscope. The DTR signal behaves incorrectly in many situations. Everything important is shown in the oscillograms.
Oscillograms.zip
Notes:

• I used a UART USB -TTL converter and a cable to the Arduino Pro Mini. It seems that the converter is equipped with a deriving RC element at the DTR output.
• There is negative logic at the UART (converter) output (Low level means ON)
• The interval between edges is variable 0.4 - 10ms and more.
• In the Connected state, it is possible to repeatedly send the same DTR/RTS value. According to the standard, these signals are not pulses, and therefore it makes no sense to repeatedly enter the same values. However, only here it may have a strange sense due to the above-mentioned signal-to-pulse conversion. But it cannot work correctly. In order to send a repeated value through the deriving circuit, two edges (positive - negative) must be sent here, which necessarily causes a RESET on Arduino and elsewhere. (BTW When repeatedly entering the same value Yes or No, you need to click on the value again for it to work correctly. You can't rely on it being already written in the window - it's a SW property)
• Disconnection works correctly.

**Edited - additional information for @knopki ** - testing DTR at the converter output without an Arduino connected:
After entering the Connect command, the SerialProjector enters the Connecting state and of course remains in it until the Disconnect command is received. The behavior of the DTR signal is correct and as expected throughout.
So it seems that the problem is perhaps related to the transition to the Receiving state.

BTW: The default screen formatting has changed. A long text string now doesn't wrap, so its beginning isn't displayed and the end has to be scrolled. I'm not happy about that.
The longest line is aligned to the center and the others (separated by "br") are aligned to the left edge of the leading text and not to the center as before. With a variable length of the leading text, the alignment of the other lines shifts. Even so, it's a step towards the better.

Typing is long and quite hard these days . But I'm trying to contribute to the development of the product.